The spleen was the most easily injured organ in the abdomen. It would also bleed massively if it was damaged. When saving patients with multiple serious injuries, the proper strategy would be to save the patient's life as the first priority, and to preserve the organs only after. When Zhang Fan reached the abdomen, he already knew that the patient's spleen and left kidney were unsalvageable.
This was really difficult and cruel! Would you want to be alive but missing a kidney and spleen? This border security military policeman patient was only about 20 years old or so, yet he would be handicapped for the rest of his life, with pain accompanying him forevermore. Right now, all Zhang Fan could do was to try to save the warrior's life as well as reduce the amount of pain he would feel afterwards.